Won't Run Without Choke On

[flrt990]

This message is a reply to an archived post by Bruce VA on July 20, 2013 at 14:29:56.
The original subject was Re: Wont Run Without Choke On.



Having a won't run without choke issue with my 1961 Ford 4000 Industrial (4cyl). Bought it barely running to get it home. Rebuilt carb then discovered the issue. Reluctantly spent the money on a different rebuilt carb and guess what, no change. It does the same exact thing. Turning adjustments does nothing. It has full fuel flow, no issues there. Discovered manifold was quite pitted and gasket seemed bad so thought I had it licked but with a (used but good) manifold and new gaskets but still no change. It has had a complete tune up. Tried bypassing ballast resistor. No change. Excellent compression. Runs smooth as silk with choke half on. It appears motor was rebuilt by previous owner. Was motor maybe beefed up and it needs a bigger venturi or nozzle??? Currently M/S TSX-813. I can't see anywhere the motor is getting the extra air. I don't know what else to check for or try. Any help you can offer appreciated.

 

[RM-MN]

Check for a weak spark. A weak spark can jump the spark plug gap with lower pressure but may not with full compression.

 

[Abbby]

Main jet is too small. Put in a larger one.

 

[showcrop]

A little info is needed if you want help.

1 What issue did you find after rebuilding the carb?

2 what does full fuel flow mean to you? No one here knows what you use for criteria or how you measured.

3. exactly where on the manifold was it pitted? and if on the mating surface is there corresponding pitting on the head?

4. What is excellent compression to you?

5. Have you tried carburetor adjustments with throttle plate fully open or only with throttle control fully open?

 

[John in Mich]

Who was it that said the majority of carb problems are spark? A weak spark requires more fuel to ignite. Thus, the choke.

 

[47fivewindow]

My N does that when the point gap is too small.

 

[Sigma.40]

My 52 did the exact same thing. Rebuilt the carb and all is good.